The so-called Easy TradeUp deal allows customers to trade in their old laptops for a discount on Microsoft computers, but there are some conditions. Your previous laptop can’t be older than 6 years, it has to have a screen that’s at least 11.4 inches, and it has to be able to power on. Customers of new Microsoft computers worth $599 or more can make their trade-in claim online.

It’s unclear how long the promotion will last, but it coincides with the release of Microsoft’s new Surface Book, which is currently available to pre-order. When the company unveiled their new product earlier this month, it called the device the “ultimate” laptop.

CNET reports that when you attempt to order one of the five versions of the Surface Book, you’re prompted with a message that reads, “Email me when available,” suggesting that the laptop is in high demand. A Microsoft spokesperson told CNET that the company has sold out of its preorder supply, and a limited number of Surface Books will be available in stores on October 26.

The Surface Book represents part of Microsoft’s attempt to revive its device sales and to demonstrate the power of Windows 10, its latest operating system.